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parser grammar EasyElParser;

options {
    tokenVocab = EasyElLexer;
}

@header {
}


@member {

    @Override
    public int getErrorLine() {
        Token token = _input.LT(-1);
        if (null == token) {
            return -1;
        }
        return token.getLine();
    }

    @Override
    public int getErrorColumn() {
        Token token = _input.LT(-1);
        if (null == token) {
            return -1;
        }
        return token.getCharPositionInLine() + 1 + token.getText().length();
    }
}

// 可计算单元：最终生成语法树的根节点
compilationUnit
    : expression?
    ;



/**
 *  链路表达式:
 *  a.b 、 a.b.c 或 a.m().f() 或 a[b] 、 a[b][c]
 */
pathExpression returns [int t]
    :   primary (pathElement { $t = $pathElement.t; })*
    ;



/**
 *  链路元素: 点、名字、参数
 */
pathElement returns [int t]
    :   dot=DOT
        namePart  { $t = 1; }
    |   arguments { $t = 2; }
    |   indexPropertyArgs { $t = 3; }
    ;


arguments
    :    LPAREN argumentList? RPAREN
    ;


argumentList
    :    argumentListElement
         (   COMMA
             argumentListElement
         )*
    ;


argumentListElement
    :    expression
    ;

expressionInParen
    : LPAREN expression RPAREN
    ;


indexPropertyArgs
    : LBRACK expression RBRACK
    ;

/**
 *  表达式: EasyEL的基本计算单元
 *  按优先级(从大到小)排列
 */
expression
    : pathExpression
    | op=(NOT | J_NOT) expression
    | op=(ADD | SUB) expression
    | left=expression op=POWER right=expression
    | left=expression op=(MUL | DIV | MOD) right=expression
    | left=expression op=(ADD | SUB) right=expression
    | left=expression op=BIT_AND right=expression
    | left=expression op=BIT_OR right=expression
    | left=expression op=(GT | LT | GE | LE | IN | NOT_IN) right=expression
    | left=expression not=NOT op=IN right=expression
    | left=expression op=(EQ | NOT_EQ | REGEX_MATCH | NOT_REGEX_MATCH) right=expression
    | left=expression op=(AND | J_AND) right=expression
    | left=expression op=(OR | J_OR) right=expression
    | <assoc=right> con=expression
            (
              QUESTION tb=expression (COLON tf=expression)?
            | ELVIS tf=expression
            )
    | tb=expression IF con=expression (ELSE tf=expression)?
    ;


forConditionExpression
    : nameList=forConditionNameList IN right=expression
    ;

forConditionNameList
    : identifier (COMMA identifier)*
    ;

/**
 *  基本计算要素：包括变量名、数字、字符串、列表和Map
 */
primary
    : literal
    | namePart
    | newInstance
    | list
    | listGenerator
    | map
    | expressionInParen
    ;

// 创建对象实例
newInstance
    : NEW constructor (props=map)?
    ;


list
    : LBRACK listItemList? COMMA? RBRACK
    ;

listGenerator
    : LBRACK item=expression FOR con=forConditionExpression RBRACK
    ;

listItemList
    : listItem
      (   COMMA
          listItem
      )*
    ;

listItem
    : expression
    ;


map
    : LBRACE
      mapEntryList COMMA?
      RBRACE
    ;

mapEntryList
    : mapEntry (COMMA mapEntry)*
    ;

mapEntry
    : mapEntryLabel COLON expression
    | MUL COLON expression
    ;

mapEntryLabel
    : keywords
    | namePart
    | stringLiteral
    | intLiteral
    | dateLiteral
    ;


namePart
    : identifier
    | nonNotKeywords
    ;

// 构造函数
constructor
    : constructorName arguments
    ;

// 构造函数名称
constructorName
    : qualifiedClassName
    ;

// 合法类名
qualifiedClassName
    : qualifiedNameElements className
    ;

qualifiedNameElements
    : (identifier DOT)*
    ;

// 类名
className
    : CAPITALIZED_IDENTIFIER
    ;


identifier
    : CAPITALIZED_IDENTIFIER
    | IDENTIFIER
    ;

// 字面量
literal
    : intLiteral
    | numericLiteral
    | stringLiteral
    | nullLiteral
    | dateLiteral
    | durationLiteral
    | booleanLiteral
    | rangeLiteral
    ;


intLiteral returns [int t]
    : INTEGER { $t = 0; }
    | LONG    { $t = 1; }
    ;

numericLiteral returns [int t]
    : NUMERIC { $t = 0; }
    | FLOAT   { $t = 1; }
    | DOUBLE  { $t = 2; }
    | DECIMAL { $t = 3; }
    ;


stringLiteral
    : STRING
    ;


nullLiteral
    : NULL
    ;


// 区间字面量: [x .. y] | [x .. t) | (x .. y) | (x .. y]
// 类似数学中的区间概念
rangeLiteral
    : LBRACK (left=expression)? DOUBLE_DOT right=expression RBRACK
    | LBRACK (left=expression)? DOUBLE_DOT right=expression RPAREN
    | LPAREN (left=expression)? DOUBLE_DOT right=expression RPAREN
    | LPAREN (left=expression)? DOUBLE_DOT right=expression RBRACK

    | LBRACK left=expression DOUBLE_DOT (right=expression)? RBRACK
    | LBRACK left=expression DOUBLE_DOT (right=expression)? RPAREN
    | LPAREN left=expression DOUBLE_DOT (right=expression)? RPAREN
    | LPAREN left=expression DOUBLE_DOT (right=expression)? RBRACK
    ;

// 日期字面量
dateLiteral
    : yyyyMMdd=DATE_YYYY_MM_DD
      time=(DATE_HH_MM | DATE_HH_MM_SS | DATE_HH_MM_SS_ss)?
    ;

// 时长字面量
durationLiteral
    : DATE_HH_MM | DATE_HH_MM_SS | DATE_HH_MM_SS_ss
    ;

// 布尔字面量
booleanLiteral
    : TRUE
    | FALSE
    ;

nonNotKeywords
    : IN
    | TRUE
    | FALSE
    | AND
    | OR
    | NULL
    | NEW
    | IF
    | ELSE
    ;

// 关键字
keywords
    : NOT
    | nonNotKeywords
    ;

